1. Field of the Invention
The present invention relates to a method of producing newspaper having a number of pages such as sixteen pages, thirty-two pages, forty pages, etc.
2. Related Art
In a known art, newspaper is produced by steps of printing a continuous web of paper in a form of a double-width size web sheet (laterally corresponding to four pages of newspaper) by using a rotary press, slitting this printed continuous web in its longitudinal direction into two portions (each laterally corresponding to two pages of newspaper) by using a slitter, overlapping the two portions and then folding them in their longitudinal direction by using a former, cutting this folded paper web in its transverse direction so as to have a predetermined vertical length of the newspaper and then delivering the same.
FIG. 4 shows a process explaining the above newspaper producing steps by using a blanket-blanket type offset rotary press. With reference to FIG. 4, the offset rotary press includes two opposed plate cylinders a, each of which is mounted with a printing plate having two lateral printing rows juxtaposed in a circumferential direction, and each of which having four printing surfaces adapted to print four pages of A, B, C and D or E, F, G and H of the newspaper in an axial direction of the plate cylinders. According to complete rotations of two opposed blanket cylinders b, a continuous web of paper c (which will be called hereinlater xe2x80x9ccontinuous webxe2x80x9d or merely xe2x80x9cwebxe2x80x9d) is printed by eight pages on respective surfaces of both sides of the continuous web. In such case, the continuous web c has a width twice a lateral width of a newspaper having four pages when the latter is opened, i.e. 1625 mm (64 inches).
Thereafter, by using a slitter, the continuous web c is slit into two portions in a longitudinal direction at an intermediate portion in a width direction of the web, and the two portions are overlapped at a gathering (collecting) section using a turn bar e. Thereafter, these overlapped portions are folded in folio in the longitudinal direction by using a former f, and then, this folded web is cut with respect to each row to thereby produce two kinds of newspapers each including eight pages, alternately in order.
At a time when the newspaper is produced by using a printing unit of a plate cylinder structure mentioned above, supposing that one printing unit has an ability for printing, for example, two kinds of eight pages, such as mentioned above, when a newspaper of sixteen, thirty-two and forty pages is printed, it is necessary to use a two-unit type, three-unit type or four-unit type rotary press having these two kinds of 8-page printing units, of which the number is increased to two (2), three (3) or 4 (four).
FIG. 5 shows a 4-unit type rotary press including four printing units g1, g2, g3 and g4. Each of continuous webs c printed respectively at the printing units g1 to g4 is divided into two parts by a slitter h, and then they are gathered by using a turn bar group of a collection unit i. Thereafter, the continuous webs c are folded in folio by former f and then again folded by a folding apparatus j.
As mentioned hereinbefore, when a newspaper is produced by using a conventional plate-cylinder type printing unit, it is necessary to increase a number of printing units every time a number of pages of the newspaper is increased, thus being disadvantageous in production cost and installation space. Particularly, the four-unit type rotary press such as shown in FIG. 5 is considerably large in size, and hence, it requires large installation space and is, moreover, expensive.
Furthermore, with such a conventional printing unit, it is difficult to increase pages of a newspaper after a first setting thereof because of limitations with regard to installation space. Moreover, in multi-color printing, since a number of printing units are required, and hence a traveling path for a continuous web is extremely elongated, there results losses in paper and time only in a paper threading process, and furthermore, much paper (web) loss results until a tension is stabilized and a different color registration is made. In addition, it is required to change a printing plate every time contents to be printed are changed, which will not be profitable in production of a small number of lots.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above, and to provide a newspaper producing method capable of producing a plurality kinds of newspapers including page numbers and colors different from each other, by utilizing a single printing unit, wherein the method is profitable for printing a small number of lots.
This and other objects can be achieved according to the present invention by providing a method of producing newspaper, comprising:
printing on both sides of a continuous web repeatedly in a printing direction, which printing includes a plurality of printing cycles each producing a plurality of lateral printed rows on each side of the continuous web, with each row having different contents relative to each other, with each row having at least two printed segments in a width direction of the continuous web, and with rows on opposite sides of the continuous web corresponding to each other;
cutting this printed continuous web with respect to each of the lateral printed rows and each two-page spread of newspaper, and setting and delivering a set of these cut portions at every printing cycle; and
folding each set of the cut portions at a longitudinally central portion of a two-page spread thereof;
whereby a newspaper of pages corresponding to the printing cycle is repeatedly produced.
In a preferred embodiment of this newspaper producing method, both sides of the continuous web are printed at a portion thereof traveling in a vertical direction. This printing is performed by using a digital printing machine including printing heads opposed to both sides of the continuous web, respectively, wherein each printing head is arranged opposite to another printing head at the same level in vertical direction. The printing may also be performed by using a digital printing machine including printing heads opposed to both sides of the continuous web, respectively, wherein the printing heads are offset relative to one another in a printing direction.
According to the present invention including the features mentioned above, both sides of a continuous web are printed repeatedly, by using a digital printing machine, in a printing direction such that this printing step includes a plurality of printing cycles each of which produces a plurality of lateral printed rows on each side of the continuous web, with each row having different contents relative to each other, with each row having at least two printed segments in a width direction of the continuous web, and with rows on opposite sides of the continuous web corresponding to each other. Therefore, a number of printed rows in a printing direction produced during a printing cycle mentioned above can be changed, and hence, it becomes possible to optionally produce newspapers different in pages and/or colors by using one set of a web feeding section and printing section. Thus, it is not necessary to increase a number of printing units, as with the conventional printing method using a rotary press, in conformity with pages and/or colors, and hence, according to the present invention, a newspaper can be produced at a reduced production cost and reduced printing system installation space.
Moreover, use of a digital printing machine makes it possible to easily change contents to be printed without changing a printing plate or the like, as with the conventional rotary press, and accordingly, only one lot printing can be performed with commercial profit.
Furthermore, since multi-color printing can be performed by using a digital printing machine which is compact, allowed for is a printing system that has a reduced web traveling path, and which can be operated with stable tension and reduced paper (web) loss during a web feeding process or different color registration process.
Further, the above and other objects, many other characteristic features and advantageous effects and the like of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.